DEFINITION MODULE GR_Attributes;

    (*
    **  Author : Peter Jardine
    **
    **  Version:
    **  1.0      17 Apr 92   New file - based on the work of 
    **                       Michael McCarthy & John Pfitzner,
    **                       CSP-960 Project, Semester 2, 1991.
    *)

IMPORT GrafCore;

CONST
    (* ======================= Colours ============================== *)

    (*
    ** Standard 4 colour CGA palette:  Black;  Cyan;  Magenta;  White;
    **
    ** Alternative 4 colour CGA palette:  Black;  Green;  Red;  Yellow;
    *)
        CGA_Black   = 0;
        CGA_Cyan    = 1;    CGA_Green  = 1;
        CGA_Magenta = 2;    CGA_Red    = 2;
        CGA_White   = 3;    CGA_Yellow = 3;
    (*
    ** 16 colour EGA/VGA palette:
    **
    **  Dark colours        Light colours
    *)
        Black     =  0;     DarkGray     =  8;
        Blue      =  1;     LightBlue    =  9;
        Green     =  2;     LightGreen   = 10;
        Cyan      =  3;     LightCyan    = 11;
        Red       =  4;     LightRed     = 12;
        Magenta   =  5;     LightMagenta = 13;
        Brown     =  6;     Yellow       = 14;
        LightGray =  7;     White        = 15;

    (* ===================== Aspect Settings ======================= *)
    DefaultAspect = 0;
    MaxXAspect    = 1;
    MaxYAspect    = 2;

    (* ======================= Write Modes ========================= *)
    (*
    ** These are made visible by the WriteMode Type declaration.
    **
    replaceMode;
    andMode;
    orMode;
    xorMode;
    *)

TYPE
    AspectSetting = [DefaultAspect .. MaxYAspect];
    WriteMode     = GrafCore.WriteMode;
                        (* replaceMode, andMode, orMode, xorMode *)

PROCEDURE GetNDCAspect(VAR aspect : AspectSetting);
    (*
    **  Get the current aspect setting in use by the NDC routines.
    *)

PROCEDURE GetBgColour(VAR colour : CARDINAL);
PROCEDURE GetRGBBgColour(VAR red, green, blue : REAL);
    (*
    **  Get the background colour being used for all display operations.
    *)

PROCEDURE GetColour(VAR colour : CARDINAL);
PROCEDURE GetRGBColour(VAR red, green, blue : REAL);
    (*
    **  Get the foreground colour being used for all display operations.
    *)

PROCEDURE GetWriteMode(VAR penMode : WriteMode);
    (*
    **  Get the current pixel placement method.
    *)

PROCEDURE SetNDCAspect(aspect : AspectSetting);
    (*
    **  Set the aspect ratio to use for NDC routines.  Legal values are 
    **  DEFAULT which uses the full resolution of the display, MaxXAspect,
    **  or MaxYAspect which may use less than the full resoultion of the
    **  display, but squares will be square, and circles will be circular.
    *)

PROCEDURE SetBgColour(colour : CARDINAL);
PROCEDURE SetRGBBgColour(red, green, blue : REAL);
    (*
    **  Set the background colour to use for all display operations.
    *)

PROCEDURE SetColour(colour : CARDINAL);
PROCEDURE SetRGBColour(red, green, blue : REAL);
    (*
    **  Set the foreground colour to use for all display operations.
    *)

PROCEDURE SetClipping(switch : BOOLEAN);
    (*
    **  Turns clipping on or off. Note that all write operations run
    **  significantly slower with clipping on. When developing programs,
    **  however, it is generally a good idea to set clipping to the full
    **  screen rectangle, and turn it on, since the low level routines
    **  perform no bounds checking whatsoever.  The default value is
    **  clipping set to the full screen rectangle and enabled.  Be sure
    **  your program does not write outside the screen area if you turn
    **  clipping off.  Attempts to write outside the screen area when
    **  clipping is disabled could have unpredictable results.
    *)

PROCEDURE SetClipRect(col1, row1, col2, row2 : INTEGER);
PROCEDURE SetNDCClipRect(x1, y1, x2, y2 : REAL);
    (*
    **  Sets the boundaries of the clipping rectangle, so that all graphics
    **  write operations are clipped to the interior and boundary of the
    **  rectangle.
    *)

PROCEDURE SetWriteMode(penMode : WriteMode);
    (*
    **  Sets the default method for interaction with background pixels in
    **  line drawing, block restoration, and char/string output.
    **  If default method is replaceMode, object overwrites the current screen
    **  contents; if the default method is xorMode, the object is XORed with
    **  the current screen contents, and so on.
    **  This function is only implemented for all write functions in EGA/VGA
    **  modes. For CGA and Hercules modes, it is only functional for WrPxl,
    **  BlockRestore, Circle and Ellipse.
    *)

END GR_Attributes.